Polarization based interferometric detector

Abstract

A sensor and method for determining the optical properties of a sample material is disclosed. The sensor comprises a light source that generates a linearly polarized light beam having a predetermined polarization orientation with respect to the plane of incidence. The linearly polarized light beam is reflected off the sample and is split into second and third light beams where the second and third light beam consist of the combined projections of mutually orthogonal components of the first light beam. A signal processor measures the intensity difference between the second and third light beams to calculate the phase difference induced by the sample material.

What is claimed is: 
     
       1. A detection device for detecting interaction between a first label-free entity and a second label-free entity, comprising:
 an optical interface comprising a surface with said first label free entity; 
 a light source for generating a first light beam comprising a first polarization component and a second polarization component, wherein said first light beam is applied to said optical interface, and wherein a phase shift between said first polarization component and said second polarization component occurs upon interaction between said first label-free entity and said second label free entity; 
 at least one optical retarder for providing a circular polarization in said first light beam downstream of said optical interface; 
 a polarizing beam splitter downstream of said optical interface, wherein said polarizing beam splitter is for splitting said first light beam into a second light beam and a third light beam after said first light beam is reflected from said optical interface; 
 a detector module downstream of said polarizing beam splitter, wherein said detector module accepts said second light beam and said third light beam and detects the intensity of said second light beam and said third light beam; and 
 a signal processing unit for receiving intensity measurements of said second light beam and third light beam from said detector module and programmed for calculating said phase shift based on the difference between said second light beam intensity and said third light beam intensity. 
 
     
     
       2. The device of  claim 1 , wherein the device is further configured to be capable of evaluating multiple complementary chemistries in a sample or a plurality of samples. 
     
     
       3. The device of  claim 1  wherein said first or second label-free entity comprises nucleic acid. 
     
     
       4. The device of  claim 1  wherein at least one of the label-free entities comprises a peptide or protein. 
     
     
       5. The device of  claim 1  wherein one of the two label-free entities is a small molecule and the other of the two label-free entities is a biological molecule. 
     
     
       6. The device of  claim 1 , wherein the device is further configured to be capable of detecting label-free nucleic acid hybridization in real time. 
     
     
       7. The device of  claim 1 , wherein the device is configured to be capable of analyzing a sample in no more than 1-2 minutes. 
     
     
       8. The device of  claim 1 , wherein the device is configured to be capable of detecting 50 femtograms of said second label-free entity in a sample. 
     
     
       9. The detection device of  claim 1 , wherein said detector module comprises:
 a first detector for measuring the intensity of said second light beam; and 
 a second detector for measuring the intensity of said third light beam. 
 
     
     
       10. The detection device of  claim 1 , wherein said first polarization component and said second polarization component are substantially orthogonal to each other. 
     
     
       11. The detection device of  claim 1 , wherein said optical retarder provides said second phase shift such that the total phase shift between said first polarization component and said second polarization component is substantially 90° before said the first beam is split into said second beam and said third beams. 
     
     
       12. The device of  claim 1 , wherein said optical interface reflects said first light beam. 
     
     
       13. The detection device of  claim 12 , wherein said optical interface is for reflecting a light beam under total internal reflection conditions. 
     
     
       14. The detection device of  claim 13 , wherein the total internal reflection conditions is total internal reflection (TIR) or frustrated total internal reflection (FTIR). 
     
     
       15. The detection device of  claim 12 , wherein said optical interface is of a transducer. 
     
     
       16. The detection device of  claim 15 , wherein said transducer containing a sensing material selected from the group consisting of antibodies, antigens, oligonucleotides, proteins, enzymes, receptors, receptor ligands, organic molecules, and catalysts. 
     
     
       17. The detection device of  claim 1 , wherein said first light beam is substantially linearly polarized. 
     
     
       18. The detection device of  claim 1 , wherein said first polarization component is in the plane of incidence, and said second polarization component is normal to the plane of incidence. 
     
     
       19. The detection device of  claim 1 , wherein said detector module comprises a chip with an array of transducers having different probes or samples at discrete sites. 
     
     
       20. The detection device of  claim 19 , wherein said chip is configured to analyze single nucleotide polymorphisms (SNPs). 
     
     
       21. The detection device of  claim 19 , wherein said chip comprises more than 100 discrete sites. 
     
     
       22. The detection device of  claim 19 , wherein said chip comprises more than 1,000 discrete sites. 
     
     
       23. The detection device of  claim 19 , wherein said chip comprises more than 10,000 discrete sites.